The Omine mine is located at about 20 km east of Tono City, Iwate Prefecture. At about 1 km northeast of this mine is found the Omine iron ore deposit of the Kamaishi mine. The geology of the Omine mine area is composed of Permian clay slate. sandstone and hornfels, intruded by granodiorite and quartz diorite. Occurrence of limestone, though not distributed on the ground surface, has been confirmed underground (at a horizon of 295m above sea level) by boring. The deposit is a copper ore deposit of a contact-metasomatic high temperature hydrothermal origin, occurring in the hornfels. The copper ore occurs as irregular masses or pipes, presenting a network or impregnation pattern. Chalco pyrite is the leading ore mineral, accompanied by a large amount of, cubanite. The ore deposit comprises five ore bodies, No. 1 (D1) to No.5 (D5), and three of them, No. 1 (D1), No. 2 (D2) and No.3 (D3), are being worked.
Since the mine was reopened in 1952, the mine area has been explored by various methods, as summarized below. a. First period (1952-1959) Improved with the working on the remaining ore of D1, the skarn zone was traced by boring and level-driving, and D2 and D3 were detected. b. Second period (1960-1961) Detailed geologic survey was made for D1 and D2. The ground surface was also surveyed in detail. Preparation for regional Prospecting of the skarn zone was made. c. Third period (1961-1962) The northern area was explored by level-driving. Scale of distribution of the skarn zone was investigated. d. Fourth period (end of 1962-1964) Detailed investigation of the detected skarn zonee was made. Ore body D4 was discovered. e. Fifth period (1964-present) Detailed investigation of D4 is in progress.
The policy of the present prospecting aims chiefly at (1) tracing of the stage of ore deposit formation and the skarn zone, and (2) confirmation of the limestone boundary. In order to gain satisfactory results efforts will be made also in clarifying the relationship between the ore deposit and the igneous rocks and the zone of fissures.

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Owing to a very limited amount of hard coking coal production in Japan, Japanese Steel Mills have been constantly seeking nearer and adequate supply source for that kind of coals at cheaper prices. They have been producing hard cokes by blending domestic soft coking coals with imported coals of which American coals were dominant until 1955 or so.
In order to fulfill these demands and upon request of the Mitsui & Co., Ltd., we have paid keen attention and made studies of the Kianga-Moura Field in Central Queensland, Australia. Through our first field survey from January to April, 1959, we gained the followinge knowledge which lead us to the conclusion as mentioned below.
(1) In Baralaba, the northern extremity of this field, occurence of anthracite had been reported in 1889 and since then the mines were opened. Many prospecting works were carried out to disclose the geological features of coal seams in and around the area. The results revealed that the coal is semianthracite or anthracite containing 10% or less volatile matter, and that the structure is somewhat contorted with NW-SE faults and folds.
(2) In Kianga, southern sector of the field, the Thiess Bros. (Qld.) Pty., Ltd., disclosed the coal seam in box-cut after prospecting by drillings. Coal is soft coking coal with 34% or more volatile matter. The coal seam has a gentle westward dip of 6-8 degrees.
(3) Judging from the geological features of the above two areas, the coal seams of both areas seem to occur in the same horizon or nearly in the same horizon.
(4) The difference in coal quality between Baralaba and Kianga is thought to be closely related to the tectonic movement by which the complicated structure of the Baralaba area was brought about.
(5) The above-mentioned, geological assumption leads to a conclusion that medium or low volatile coal with a possibility of hard coking coal, may be concealed underneath the vast uninvestigated plain between Baralaba and Kianga, covering a distance of 60 km.
From the said point of view, the second prospecting work was commenced in June, 1959 to search for hard coking coal required by the Japanese Steel Mills, with the cooperation and support of the Thiess Bros. and Mitsui & Co. Strenuous efforts revealed that our geological conjecture was right, that is, volatiles in coal seams decrease from south to north, and the samples extracted from a trial shaft at Moura, the central part of the field that was selected by us as a hopeful place for aimed coal, of large reserves, were proved to be hard coking after many tests by the Japanses Steel Mills. This was in November of 1960.
Exploitation of the Moura Mine was thus inauguarated in January of the following year and the first shipment of the Moura un-washed coal was delivered to Hirohata of the Fuji Steel Mill in August. The development has since progressed in rapid strides. In the fisycal year of 1964, the mine is to offer a total output of one million tons of hard coking coal with low sulpher content (less than 0.5%) and low ash content (less than 6%) to the Japanese Steel Mills, at cheaper price than other Australian coals, not to mention American coals. Furthermore, a bright future was promised. A long-term contract for thirty million tons of coal in thirteen years from 1965 was concluded between the Japanese Steel Mills and the Thiess-Peabody-Mitsui Coal Co., operator of the Moura Mine.
This paper deals with the methods of prospecting, such as geological field investigation, surveying, aerial photograph interpretation, as well as drilling and sampling. It also describes a brief history and the present status of the Moura Mine.

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Ore deposits of the Sipalay Mine are of the disseminated copper type occurring in quartz-diorite porphyry and in the surrounding meta-volcanics near the contact.
Detailed geological mapping and structural analysis of the known deposits led to the discovery of a new huge deposit under an alluvial plain.
The following geological interpretations were used successfully to locate the new ore body:
1) The shape and locus of igneous intrusions were influenced by a fissure pattern developed successively by (a) a shear couple (E-W and N-S) with northeasterly tension and northwesterly compression, and (b) northeasterly lateral compression.
2) Although the main quartz diorite intrusive is elliptical in plan and elongated parallel to tensional fractures, the laters differentiates were squeezed out beyond the periphery of the main mass, especially along the northeasterly and northwesterly fissures. These porphyritic offshoots are considered to be closely related to the copper mineralization.
3) Shattered zones formed by the intersection of fissures along the four main directions in and adjacent to the porphyritic offshoots provided a favorable setting for ore concentration.

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A mining geological prospect should clarify minute evidences in the variation of coal seam in a limited area of mine or pit under development. Discovery of regularity in variation of coal seam will be made geologically and statistically, treating the evidences and measured data as a microgeohistory of a certain point within the coal-forming basin. This will make the prospect more successful.
Directions of stable elongation of the coal seams of the Bibai coal-bearing formation are similar to those of sediments intervened between coal seams, consisting of major 30° upwards trend to the north and minor 30° upwards trend to the south from the horizon on the steeply dipping (70°±) bedding plane with N-S strike; the former is parallel to the general elongation of the basin that has been recognized in the isopach map of the formation of the whole area of the basin when the bedding is pictured horizontal by turning around its strike line, and the latter which crosses and links the more stable former elongations is thought to have occurred during peat accumulation and conservation, and have been orientated parallel to the prominent trend of faults within this area by an embryonic factor of this movement.
By regression analyses a significant linear correlationship is recognized between the thicknesses of successive coal seams and underlying sediments, and the proportion of coal material in a coal seam and underlying sediments. The regression equation (y=ax+b) can explain mathematically the development of coal seams and fluctuation of the coal-forming conditions in the basin. A tentative diagram of average interval thicknesses between coal seams as time function versus relative values of coefficient (a) and constant (b) of the equation would be called a transitional development curve of successive coal seams.
Discovery of these regularities of directional properties and correlativities is effective for predicting variations in coal seams at deeper places, for providing the basis of extensive application of boring data obtained from one point, and also for ascertaining whether the variations are continuous or not.

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The copper ore bodies of the Yaguki mine, Fukushima Prefecture, are of high-temperature replacement type, occurring in limestone along its contact with underlying slate. The Dai-ichi ore body, which is the largest one in the mine, is localized in the main synclinal portion of the system of gently plunging folds. The skarn minerals are zonally arranged from the limestone side to the slate side as follows: limestone -"green skarn" (clinopyroxene-epidote-amphibole skarn)- garnet skarn -"banded skarn" (epidote-carbonate-quartz skarn)- slate. Chalcopyrite, magnetite and pyrrhotite are the main constituents of ore body, with minor amounts of sphalerife, pyrite, arsenopyrite, molybdenite, bismu-thinite, cobaltite, cubanite, galena and hematite. The zonal distribution of ore minerals around quartz diorite mass is remarkable in the upper part of the ore body. The crystallization of pyrrhotites may be divided into two stages, judging from their modes of occurrence and chemical compositions. The earlier pyrrhotite has commonly a lower atomic ratio of metal content than that of the later. There is a variation of atomic ratio of metals in the earlier pyrrhotites from top levels to the bottom, and the tendency is reverse in the later pyrrhotites.

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The ore deposits of the Hanaoka mine are of the 'Kuroko' type. The 'Kuroko' deposits generally occus as bedded or tabular bodies in the Tertiary formation in Japan. In the 'Kuroko' area, the following rocks are found in ascending order: dacite, pyrite-bearing siliceous rock, gypsum ore-body. pyrite ore-body, chalcopyrite-pyrite ore-body, chalcopyrite-barite-galena-sphalerite ore-body and oxide bed. The oxide bed consists characteristically of manganite and hematite. The principal mineral assemblages of the oxide bed are as follows: 1) manganite-'pink colored montmorillonite' or montmorillonite alone, 2) hematite-quartz in nodule and sericite-quartz in host. The radiolarian fossils were found to be rather commoner in the siliceous part than in the clayey part of the bed. Judging from the existence of many radiolarian fossils, the oxide bed might be deposited like ferruginous chert in sea water. Close field relationship of the 'Kuroko' deposit with the oxide bed suggests that the former is of the submarine exhalative sedimentary type.

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